The thing is very few people will actually meet the criteria for a full-fledged disorder diagnosis. Just playing a lot of video games--even if a person spends every last minute of their free time doing that--does not rise to the that level. We are talking people who cannot hold down a job because they can't stop playing video games, who cannot take care of themselves or others because of their need to keep playing. And this isn't even about people who make bad choices because they enjoy gaming so much that they stay up late and miss work or school, or have lost real world relationships because they enjoy their virtual worlds more. No, just the fact that the person is actually making a choice in these circumstances, poor as it may be, means it does not meet the criteria for a pathological diagnosis. Someone who has this disorder is incapable of making any other choice but to play, just as someone with OCD is incapable of choosing to ignore their compulsion.

People throw around the addiction terms, but they are not entirely synonymous with the disorders. There are many more people who meet the criteria for addiction than have a full-fledged disorder. But those that have the disorder would likely qualify for disability, just as people with other forms of mental illnesses that keep them from working (like OCD, Agoraphobia, Severe Depression, Schizophrenia, etc) would qualify.